Anti-DNA.RNA sera. Specificity tests and application in quantitative in situ hybridization

The specificity of anti-nucleic acid antisera can immunocytochemically be evaluated with test systems which apply various nucleic acids immobilized to inert matrices. When using polyrA.polyrU as a model compound for dsRNA, it is important to prevent the formation of the triple stranded form polyrA.(polyrU)2. Anti-dsRNA antibodies which, when tested with the correct test system, proved to be present in an earlier described anti-DNA.RNA serum, could be removed by adsorption. By cytofluorometric comparison of the immuno-fluorescence signals obtained with the anti-dsRNA containing serum and the absorbed serum, it could be shown that the anti-dsRNA antibodies do not contribute to the specific signals measured after in situ hybridization. Repetitive incubations with the anti-DNA.RNA serum led to a considerable increase in immunofluorescence signal.